University of Alaska Fairbanks

University of Alaska Fairbanks

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Invertebrate Length-Weight Regression Parameters

Terrestrial and aquatic invertebrates are an important part of riparian ecosystems, and are a major part of the diet of juvenile salmon. Invertebrate mass may be estimated from measurements of their length using the allometric formula W = aL^b ; where W is the total dry body mass, L is the total body length, and a and b are the constants of the regression between W and L. In the EPSCoR Southcentral Test Case, we are using these relationships as a tool in investigating how riparian vegetation influences invertebrate prey subsidies and diet proportions of juvenile Chinook and Coho Salmon.

We compiled a database of length–mass regression constants a and b for prey items found in juvenile salmon diets. The database includes values from published literature (Rogers et al. 1976, 1977; Smock 1980; Benke et al. 1999; Johnston and Cunjak 1999; Sabo et al. 2002; and others) and from Alaskan stream invertebrates (M. Wipfli, unpublished data). The database also includes parameter values used to estimate the wet mass for prey fish using taxon-specific length and mass measurements (AEA 2014, Fleming and Ng 1987). We used the resulting wet mass of prey fish and salmon eggs to estimate dry mass using percent dry mass values of 24.9% for Oncorhynchus spp., 22.5% for sculpins, and 40% for fresh salmon eggs (Ashton et al. 1993; Brey et al. 2010).

See Contacts section for individuals with further information on methods and applications of this database.

Data and Resources

  • Download
    Download :: Invertebrate Length-Weight Parameters Database

    LW_parameter_database_20180604.xlsx (206 KB)

Status: Ongoing
Type: Data
Data Types: Database
Primary Contact
Wipfli, Mark
Professor of Freshwater Ecology, UAF
Work: (907) 786-1637
Primary Agency
University of Alaska Fairbanks

Funding Agency
EPSCoR - Alaska Adapting to Changing Environments

Other Agencies
USDA Forest Service, US Geological Survey

ISO Topics
biota, environment, inlandWaters


Alaska EPSCoR Southcentral Test Case - Aquatic Ecology Study

Source Portal
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